1. Field of the Invention
The present invention relates to a transponder, more particularly to a transponder, in particular to a transponder with a built-in sensor and a sensing system the transponder.
2. Description of the Related Art
Known ways of communication by a sensing system of this kind include communication using a reader/writer and a transponder. In this way of communication, the reader/writer utilizes the unique identifier (ID) of the transponder.
First, in order to identify individual transponders, the reader/writer has to cause each transponder to transmit its ID. Therefore, the reader/writer transmits to each transponder an identification command to have ID information sent.
In communication using a reader/writer and a transponder, if the reader/writer communicates back to a plurality of transponders at the same time, different signals will collide with one another. This would make it impossible for the reader/writer to recognize the ID of each transponder. To overcome this problem, in order to ensure accurate recognition of the ID of each transponder, the reader/writer is provided with a function to control return communication from transponders.
By utilizing this function, the reader/writer acquires the ID of every transponder. After completing the acquisition of IDs, the reader/writer sends a command to designate a transponder and have its internal processing done. After completing the internal processing, the transponder transmits to the reader/writer a message to notify the completion.
Upon confirmation of the completion of internal processing by the transponder, the reader/writer transmits and receives similar information to and from another transponder and repeats this procedure until such transmission/reception is completed for every transponder.
The presence of a sensor built into a transponder makes it possible for the sensed result by communication. Further, the transponder with the built-in sensor can be reduced in size to about the dimensions of an integrated circuit size by using semiconductor integrated circuit technology for its configuration. The smaller the size of the transponder is, the greater the variety of purposes it can be applied to.
Incidentally, known examples of the prior art of data processing system between a plurality of transponders and one reader/writer or of a processing system using wireless communication between a plurality of handsets and a base unit include the following.
Japanese Patent Application Laid-Open No. 2000-224674 (Patent document 1), relating to a radio telemeter system, discloses a radio telemeter system, including a base unit and a handset constitutes a group, by which the discrimination of a radio unit is accomplished more quickly by transmitting a signal specifying the group (group ID) following a communication synchronizing signal (radio header) and the reception is started with the group specifying signal thereby to reduce the duration of the state of reception.
Japanese Patent Application Laid-Open No. Hei 10-293893 (Patent document 2), relating to a radio meter inspection method for consecutively collecting information from meters connected to a handset, discloses a method according to which an external device and a base unit are line-connected, the base unit and a handset are connected by a wireless line under the control of the external device, the line connection between the external device and the base unit is not cut off after the completion of the collection of measurement information from a measuring tool connected to the handset, but the base unit is wireless-connected again to another handset under the control of the external device and continues to collect the next set of measurement information from the measuring tool connected to that other handset.
Japanese Patent Application Laid-Open No. Hei 08-273088 (Patent document 3), relating to a radio meter inspection method of inspecting measuring tools such as city water meters or city gas meters by using electric waves, discloses a method according to which the meter to respond is specified by transmitting in a meter inspection request telegraphic message a few designated ones among the digits of the ID number of each of the meters to be collectively inspected, such digits being successively transmitted for these meters, and each meter having received the inspection telegraphic message, if the ID containing the designated digits is found identical with its own ID, returns the reading of the meter following the sequence of the transmitted IDs.
Japanese Patent Application Laid-Open No. Hei 05-041888 (Patent document 4), relating to a broadband data collection system, discloses a broad band data collection system including individual house data sending means, provided for each house, for converting the data of the consumed quantity of electric power, city water or city gas into a required high frequency signal and sending it byway of an electric wave; small group data receiving means, provided for each group consisting of a plurality of houses, for receiving the electric wave from the individual house data sending means and demodulating it into data; and broad band data collecting means for collecting the data on individual houses received by a plurality of the small group data receiving means via a communication line or the like, wherein the individual house data sending means is provided with a memory unit for storing house codes preset for the identification of houses and type codes preset for the identification of data types, and an identification code matching the house code and the type code read out of the memory unit is added to the head or the like of each set of data and sent out.
Patent document 1: Japanese Patent Application Laid-Open No. 2000-224674
Patent document 2: Japanese Patent Application Laid-Open No. Hei 10-293893 Patent document 3: Japanese Patent Application Laid-Open No. Hei 08-273088
Patent document 4: Japanese Patent Application Laid-Open No. Hei 05-041888